Spark-plug



J. BROOKS.

SPARK PLUG. APPLICATION-FILED sun-29. I919.

Patented May 11, 1920.

R M m a A770 NEYS 45. and centers the core in the shell.

I UNITED- s'r-ArEsrnTENT. OFFICE.

JAMES snacks, or MOUNT VERNON. NEW YORK, ASSIGNOR TO MATTHEW HAWE. OF

PELHAM MANOR, NEW YORK.

SPARK-PLUG.

Specification of Letters Patent.

Patented May 1 l. 1920.

. Application filed September 29. 1919. Serial No. 327,227.

plug for use in internal combustion engines. The object is to provide a construction which facilitates the rapid and economical production thereof, and which affords in the finished article great durability.

In the accompanying drawing, the single figure is a vertical sectional view of the complete plug.

1 represents the shell or main body which has a central ,unthreaded passage therethrough. T he lower part of said passage is counterbored to form a shoulder 2. The

lower part ofi-the shell is provided with the usual external thread 3, while the upper part is preferably provided with a hexago'nal head to receive a wrench. 5 is a contact point at thelinner end of the shell l.

The shell 1 is easily and quickly produced by a very simple machining operation and requires only one threading operation. 6 is a central pin, the inner end of which constitutes the second contact point and 0 which as shown, 'inay be bent so as to lie .close to the contactipoint 5, the space hetween the two being adjustable in the usual manner so as to afl'or'cl'the proper gap across which the spark has to jump. 7 is a shoulder near the inner end of.the "pin. ,8 isa sleeve of insulating material oca'ted Faround themiddlelportionbf the pin 6 and against the shoulder 7, said insnlation being of any suitable material such whis'inieas 918:8, sleeverojf any] suitable matey rial such as irontr steel which is fixed tightly. on the insulating sleeve 8 so as to;

, permanently bind the same inplace. The a sleeve!) also forms a holding shoulder 10 When the parts are assembled, the external diameter of the sleeve 9 makes an easy sliding fit Within the lower end of the counterbored portion of the shell 1. His a packing washer between the shoulders 2 and; 10.

12' is" ablock of insulating 'material having a central passage arranged to' slide over the outer end of lt hei )in' 6 and to stand over the adiacent peetion ofthe-inll tightly against the shoulder 2.

vsage therethrough forming an saluting material 8 which surrounds said pin. 14 is a nut which is threaded on the outer end of the pin 6 to hold the insulat- 'ing block 12 firmly against the outer end of the shell 1 and which at the same time serves to'draw the shoulder 10 and washer 15 is a lock nut for the nut 14. Wis the usual binding-post thumb nut which is arranged to hold the end of a "conducting wire in electrical engagement with the pin 6. 17 is a packing washer which may; be provided if desired between the upper face of the shell land the lower face of the block 12.

The blockl2 is preferably made of a material capable of resisting fracture, for example,a compressed asbestos compounihor it may be made of a heavy piece of porcelain like material, however, I prefer to use the former material since it will resist severe usage. It will be noted that the removable eore, comprising the central pin. the;

insulating sleeve 8, and the metallic sleeve 9, is loaded into the shell from the inner or lower end insteadof from the outer end, which latter practice is the customary one. This new method of assembly is not only simple but it also avoids the necessity of providing any internal threading of the shell thereby greatly clicapening the man ufacturing cost. if desired the binding sleeve 9 may have a slight internal taper so' as to further resist any tendency to slip, or slide on the insulating sleeve 8 when drawn into place by nut 14;

I claim A spark plug comprising a metallic shell having, a ongitudinal counter-bored pasal shoulder the inner bore of sa d passage being larger than the outer .bore .a ,thread on the outer side of the inner endfof" said shell',

a removable core comprising ,a'inetallic pin having a fixed metallic sliould er near its inner end and threaded atgitsf outer end,

an insulating sleeve satrrmuidin g the mid- (llQPOI'tlOIl of saidpm and bearing against -:said shoulder; a "metallic centering sleeve surrounding said insulating sleeve intermediate the length thereof and fixedly mountedthereon against independent longitudirial movement. that part of the insulating sleeve between said centerin sleeve and the threaded portionof the pin; eing of greater length then the smaller portion of the 'counterbore in the shell so as to project above the outer e said shell, 2; sepa rate insulating pi ice mounted on the outer end of the shell and surrounding that part of the insulating sleeve which projects above the shell, and a clamping nut mounted on the threaded part of said pin and bearing against said insulating piece and operatin to draw said centering sleeve toward said 10 stop shoulder within the shell to hold said parts rigidly assembled.

JAMES BROOKS. 

